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Category: Mechanics

Question-51539

Question Number 51539 by ajfour last updated on 28/Dec/18 Commented by ajfour last updated on 28/Dec/18 $${Rope}\:{has}\:{a}\:{total}\:{length}\:{L}\:{and}\:{linear} \\ $$$${mass}\:{density}\:\rho.\:{System}\:{is}\:{released} \\ $$$${as}\:{shown}.\:{The}\:{pulley}\:{is}\:{a}\:{disc}.\:{Find} \\ $$$${time}\:{it}\:{takes}\:{for}\:{the}\:{rope}\:{to}\:{unwind} \\ $$$${completely}.…

Zombie-apocalypse-has-started-You-are-at-point-A-3-2-At-point-B-5-4-there-is-a-shelter-A-river-flows-along-the-X-axis-You-are-running-at-a-constant-velocity-1-ms-1-with-an-intention-to-r

Question Number 182405 by abdullah_ff last updated on 09/Dec/22 $${Zombie}\:{apocalypse}\:{has}\:{started}.\:{You} \\ $$$${are}\:{at}\:{point}\:{A}\:\left(\mathrm{3},\mathrm{2}\right).\:{At}\:{point}\:{B}\:\left(−\mathrm{5},\mathrm{4}\right) \\ $$$${there}\:{is}\:{a}\:{shelter}.\:{A}\:{river}\:{flows}\:{along}\: \\ $$$${the}\:{X}\:{axis}.\:{You}\:{are}\:{running}\:{at}\:{a}\:{constant} \\ $$$${velocity}\:\mathrm{1}\:{ms}^{−\mathrm{1}} \:{with}\:{an}\:{intention}\:{to} \\ $$$${reach}\:{the}\:{shelter}\:{but}\:{before}\:{that},\:{you} \\ $$$${have}\:{to}\:{reach}\:{the}\:{river}\:{and}\:{fill}-{up}\:{your} \\ $$$${water}\:{jar}.\:{What}\:{is}\:{the}\:{lowest}\:{time}\:{it}\:…

If-a-number-of-little-droplets-all-of-the-same-radius-r-coalesce-to-form-a-single-drop-of-radius-R-show-that-the-rise-in-temperature-is-given-by-3T-pJ-1-r-1-R-where-T-is-surface-tension

Question Number 51325 by peter frank last updated on 26/Dec/18 $${If}\:{a}\:{number}\:{of}\:{little}\: \\ $$$${droplets}\:{all}\:{of}\:{the}\:{same}\: \\ $$$${radius}\:{r}\:{coalesce}\:{to} \\ $$$${form}\:\:{a}\:{single} \\ $$$${drop}\:{of}\:{radius}\:{R}.{show} \\ $$$${that}\:{the}\:{rise}\:{in}\:{temperature} \\ $$$${is}\:{given}\:{by} \\ $$$$\frac{\mathrm{3}{T}}{{pJ}}\left(\frac{\mathrm{1}}{{r}}−\frac{\mathrm{1}}{{R}}\right)…

A-ball-is-bouncing-down-a-flight-of-stairs-The-coefficiate-of-restitution-is-e-The-height-of-each-step-d-and-the-ball-descends-one-step-at-each-bounce-After-each-bounce-it-rebounds-to-heigt-h-above

Question Number 51107 by peter frank last updated on 24/Dec/18 $${A}\:{ball}\:{is}\:{bouncing}\:{down} \\ $$$${a}\:{flight}\:{of}\:{stairs}.{The}\: \\ $$$${coefficiate}\:{of}\:{restitution} \\ $$$${is}\:{e}.{The}\:{height}\:{of}\:{each}\:{step} \\ $$$${d}\:{and}\:{the}\:{ball}\:{descends} \\ $$$${one}\:{step}\:{at}\:{each}\:{bounce}. \\ $$$${After}\:{each}\:{bounce}\:{it}\:{rebounds} \\ $$$${to}\:{heigt}\:\:{h}\:{above}\:{the}\:{next}…

Question-50973

Question Number 50973 by Necxx last updated on 22/Dec/18 Answered by mr W last updated on 22/Dec/18 $${see}\:{Q}\mathrm{50913}. \\ $$$${t}_{\mathrm{1}} =\mathrm{2}{e}\sqrt{\frac{\mathrm{2}{h}}{{g}}}=\mathrm{2}\left(\frac{\mathrm{3}}{\mathrm{4}}\right)\sqrt{\frac{\mathrm{2}×\mathrm{20}}{\mathrm{10}}}=\mathrm{3}\:{seconds} \\ $$ Commented by…

The-range-of-riffle-bullet-is-1000m-when-is-the-angle-of-projection-if-the-bullet-is-fired-with-the-same-angle-from-a-car-travelling-at-36km-h-towards-the-target-show-that-the-range-will-be-incre

Question Number 50915 by peter frank last updated on 22/Dec/18 $${The}\:{range}\:{of}\:{riffle}\:{bullet} \\ $$$${is}\:\mathrm{1000}{m}\:{when}\:\theta\:{is}\:{the}\:{angle} \\ $$$${of}\:{projection}.{if}\:{the}\:{bullet} \\ $$$${is}\:{fired}\:\:{with}\:{the}\:{same}\: \\ $$$${angle}\:\:{from}\:{a}\:{car}\:{travelling} \\ $$$${at}\:\mathrm{36}{km}/{h}\:{towards}\:{the}\:{target} \\ $$$${show}\:{that}\:{the}\:{range}\:{will} \\ $$$${be}\:{increased}\:{by}…